Grounding connection



. 2, 1941. A. BARNsTr-:INER

GROUNDING CONNECTION Filed Dec. 29, 1939 2 Sheets-Sheet l 2, 1941. A.BARNs-rr-:INER

GROUNDING CONNECTION 2 Sheets-Sheet 2 ril,...

Fin...

v v INVENToR /7/f0/7s Bar/7J e/n en WITNESSES:

ATTORNEY Patented Dec. 2, 1941 2,264,271 GIIOUNDING CONNECTION Alion:Barmteiner, Manleld, Ollio, signor to Westinghouse ElectricManufacturing Ccmpany, East Pittsburgh, Pa., a corporation ofPennsylvania Applicaon December 29, 1939, Serial No. 311,831

4 Claiml. (Cl. 21B-37) My invention relates to range heaters and moreparticularly vto a method of grounding such heaters.

Enameled supporting structures have been and are being used to a greatextent for various types of heating units, such as range surface unitsand oven heaters, or the like. Safety requirements demand that suchstructures be grounded. A satisfactory grounding of such enameledstructures requires that the grounding connection be rmly connected tothe metallic base or understructure which, by necessity, due to theenamel protective coating thereon is formed of a corrosive metal.

Such connection has heretofore been made directly with the corrosivemetallic structure, and although various methods have been employed tomake the necessary grounding connection, in all cases a portion of theenamel protective coating was required to bc removed from the corrosiveunderstructure. Quite frequently, the enamel has not been properlyremoved, thus leaving a portion of the base about the groundingconnection without a covering of protective enamel. The corrosive metalis thus free to deteriorate, resulting in the possibility of thegrounding connection becoming disengaged or electrically disconnectedfrom the supporting structure. Such ungrounded structure is then a verydangerous hazard capable, under some conditions, of serious injury to anoperator contacting it. y I

To overcome this serious hazard which has retarded the use of enameledheating unit supporting structures, I propose to utilize a non-corrosiveelectrically conducting grounding or contact member which may be rigidlyattached to the corrosive supporting structure without the need ofremoving the protective coating from that structure.

' It is, therefore, an object of my invention to `provide a groundingdevice ior enameled structures which may be rigidly attached to suchstructures before applying the enameling coating thereto.

A further object of my invention is to provide a corrosive metallicenamel-adhering heatingunit-supporting structure with a metallic,noncorrosive, non-oxidizing, electrically conducting grounding orconnecting device to which an enamel coating will not adhere, as agrounding device therefor.

Another object of my invention is to provide a method of grounding anenameled structure by attachingv a non-corrosive metallic member to suchstructure exclusive of such member and then connecting the desiredgrounding device to such member.

Still a further object of my invention is to provide a grounding memberfor an enameling structure which may be subjected to the usual enamelingspray or dipping process but which will not retain the enamel coatingduring the baking operation whereby such coating will automatically beremoved from the grounding member during such baking operation.

Other objects of my invention will either be pointed out specifically inthe course of the following description of a device embodying myinvention, or will be apparent from such description.

In the accompanying drawings:

Figure l is a bottom plan view of a heating unit embodying my invention;

Fig. 2 is a sectional view taken along the line II-II o! Fig. l;

Fig. 3 is a fragmentary, enlarged sectional view similar to Fig. 2;

Fig. 4 is a top plan view of an oven heating structure embodying myinvention; and

Fig. 5 is an enlarged sectional view taken along the line V-V of Fig. 4.

Referring to Figs. l, 2 and 3 of the accompanying drawings, in whichlike reference characters indicate like parts in the several figures, Ishow a range surface unit heating structure Iii comprising an enameledsupporting structure I2 and a heating element I4 rigidly attached to thestructure I2, the enameled supporting structure I2 having non-corrosivemetallic members I6a and I6b attached thereto for permitting thestructure I0 to be adequately grounded.

The heating unit I0 is, in this instance, of a well-known structure inwhich the heating element I4 is formed of a plurality oi' complementaryplates with electric resistors insulatedly positioned therebetween andis rigidly attached to a supporting pan-like structure I2 by means of asuitable bolt-like member I8. It is to be understood that any desiredheating element may be used in lieu of element Il. The bolt-like memberI8 is rigidly attached to or integral with the heating element I4 anddepends'therefrom, at substantiallythe mid-point thereof. The bolt I8 isadapted to pass downwardly through a suitable insulating member 20positioned within the pan I2 and through a centrally located aperture 22in such pan structure I2. A suitable nut 24 is then positioned upon thelower end of bolt IB drawing the heating elesuch structure. applying acoating of enamel to ment Il down against the insulating member and panstructure I2 to form a functionally integral heating unit I0.

The enameled supporting structure I2 is formed of an oxidizing orcorrosive enamel-adhering metallic sheet I3 in a well-known manner. Suchmetal is preferably a commercial vitreous enamel iron of rather highpurity. By having the pan structure I2 formed of an enamel-adheringmetal, such structure may be readily enameled in any well known manner.However, if the pan structure I2 be wholly enameled, it follows that theheating element I4 will be electrically insulated therefrom.Accordingly, to adequately ground the element and pan structure, it isnecessary to provide electrically connecting means therebetween, asherein described. Suitable depending ears 26 are formed within the lowersurface of pan structure I2 to permit a 'terminal block 28 to be rigidlyattached theretoin a well-known manner. The terminal block 28 retainsthree ends of suitable terminal straps which are l onnected to terminals32 of the heating element I4. The depending ears 26 are integral withthe pan structure I2 and are `enameled therewith in the usual manner.These ears 26` retain the insulating block 28 by means of suitablethrough bolts 34 which pass therethrough.

Suitable non-corrosive, non-oxidizing, enamel-non-adhering, electricallyconducting, washerllke members |6a and. I 6b are rigidly attached to thecorrosive metallic sheet I3 used in forming the pan structure I2. Thesenon-oxidizing washers are preferably of a high temperature copper nickelalloy which are lowin iron content such as is sold under the trade nameMonel. The washers 16a and I6b are rigidly attached to the pan structureI 2in any desired manner. However, it is preferred that they be spotWelded thereto. One washer I6a is positioned about the aperture 22coaxial therewith. A second washer I6b is positioned on one of thedepending ears 26 of the pan structure I2 to provide means forconnecting, say, grounding means to such structure.

After rigidly attaching the non-oxidizing enamel-non-adhering washers tothe corrosive metallic base metal I3 of the supporting structure I2,such structure is enameled, usually by the spraying method, so as toprovide a suitable enameled coating therefor. The enamel is then bakedon in a well-known manner to provide a suitable non-corrosive,electrically non-conductive coating for the supporting structure I2.Some of the enamel coating will be deposited upon the washers during thespraying operation. However, inasmuch as the washers I6a and I6b arenon-oxidizing and enamel-non-adhering, the enamel coatingunintentionally sprayed upon the washers will not adhere thereto. Suchenamel is drawn off the washers during the baking or ring operationbecause of the non-oxidizing and enamel-non-adhering characteristic ofthe washers by the surface tension of such enamel coating prior tosolidication thereof. Accordingly, there will be no corrosive coatingpositioned upon the washers after the baking operation.

It therefore'follows that there will be an electrical connection betweenthe uncoated, nonattached to the supporting structure I2 by means of theelectrically conducting bolt I8, it follows that such element I4 iselectrically associated with the metallic supporting structure I2, dueto the bolt I8 being intimately associated with such element I4 at oneend thereof and operatively associated with the metallic washer I 6through nut 24 at the other end thereof. The heating element I4 is thusgrounded to or electrically associated with the enamel coated structureI2.

The pan structure I2 is grounded by means of one of the elongated bolts34 which rigidly attach the terminal block 28 to the supportingstructure. The elongated bolt 34 passing through the washer I6b andterminal block 28 is rigidly attached thereto by means of a suitable,wing-nut 36. A suitable grounding wire 38 may thus be positionedbetween the terminal block 28 and wing-nut36, so as to make electricalcontact therewith. vThe enamel supporting structure I2 is thus groundedby means of wing-nut 36, elongated bolt 34 and non-corrosive washer I6b,which is rigidly attached thereto.

The heating element I4 is thus electrically associated with or groundedto the enamel coated supporting structure I2 by means of non-corrosivewasher IIa. The combination structure of the supporting member I2 andheating element I4 is then grounded by means of the second washer I6band wing-nut connection 36 to the grounding wire 38.

It is therefore obvious that I have provided an article of manufacturecomprising an oxidizing, corrosive, enamel-adhering, metallic structurewith a vnon-oxidizing, non-corrosive, electrical conducting,enamel-ncn-adhering member rigidly attached to said structure, and inelectrical contact therewith, for providing means for grounding-thecorrosive metallic structure or for attaching an electrical connectionthereto, such structure but not said member being covered with anon-corrosive, electrically non-conducting, protecting coating.

Referring to Figs. 4 and 5, I show a second form of a protectivelycoated heating unit. Such yheating unit 40 comprises a Vmain structure42 and a suitable heating element 44 insulatedly attached thereto. Theheating unit 40 herein described and illustrated is more fully describedand claimed in a copending application Serial No. 311,617, filedDecember 29, 1939, of E. H. Lockwood, assgned to the assignee of thisapplication. The structure 42 is likewise formed of a corrosiveenamel-adhering metallic sheet 46,-

l terial as washers I6a and I6b) is rigidly attached to the corrosivesheet 46 about 'the aperture 48 in electrical communication therewith.

The corrosive enamel-adhering sheet 46, with the metallic washer 50attached thereto, is then enameled in any desired manner, such as byspraying. However, due to the washer 50 being enamel-non-adhering, theen'amel coating 52 will not remain upon such washer, as hereinabovedescribed. Such enamel coating Will, however, extend down within theaperture 48 adjacent the washer 5U. l

It, therefore, follows that any desirable and suitable grounding member54 may be rigidly attached to the washer 50 so as to be in electricalcommunication with or ground the enameled supporting structure 42 of theheating unit Il).

It is, therefore, obvious that I have provided a method of grounding anenameled or protectively coated corrosive metallic structure whichpermits such structures to be grounded without the need of wiping orremoving the protective coating therefrom at any stage of the process ofcoating such structures. Further, that such grounding member will permitany desired or necessary grounding structure to be rigidly attached tothe corrosive metallic structure without harming the protective coatingthereon.

It is to be understood that the electrical connection with the enameledstructures, through the medium of the enamel-non-adhering membersattached thereto, need not be for grounding purposes alone but may beused for making any desired electrical connection with an enameledstructure,

Various further modifications may be made in devices embodying myinvention without departing from the spirit and scope thereof, and Idesire, therefore, that only such limitations shall be placed thereon asareimposed by the prior art and the appended claims.

I claim as my invention:

1` An article of manufacture comprising a corrosive metallic structure,a non-corrosive member rigidly attached to such structure and inelectrical contact therewith, said structure alone being covered with anon-corrosive protecting coating, and contact means attached to saidmember for making electrical contact with the structure.

2. An article of manufacture comprising a grounding member, a corrosivemetallic structure, having an aperture therethrough for permitting thegrounding member to pass therethrough, a non-corrosive electricalconducting member attached to said structure adjacent the aperture andin electrical contact therewith, said structure alone being covered witha non-corrosive electrically non-conducting protecting coating, and saidgrounding member passing through the aperture and engaging thenon-corrosive member rigidly attached to the structure for ground- .ingsuch non-corrosively coated structure.

3. A heating unit comprising, in combination, a heating element, acorrosive metallic supporting pan structure, a plurality ofnon-corrosive metallic members rigidly attached to the pan structure inelectrical contact therewith, a non-corrosive electricallynon-conducting enamel coating covering such pan structure alone,v meansfor attaching the heating element to such pan struc-4 ture, said meansengaging one of the non-corrosive members for grounding such element tothe pan, and means comprising a second noncorrosive member for groundingthe pan structure and heating element. A

4. A heating unit comprising, in combination, a heating element, acorrosive metallic heat shield adapted to' support such element, anon-corrosive metallic washer rigidly attached to the shield coaxiallywith an aperture therethrough, a noncorrosive electricallynon-conducting enamel coating covering the shield alone, a groundingbolt passing through the washer and aperture,4

and nuts threaded upon such bolt for rigidly attaching it to the shieldand washer for providing electrical connection from such bolt to thewasher and shield.

ALFONS BARNSTEINER.

